Art of evaporating liquids



H. J. ZIMMERMANN.

ART OF EVAPORATING LIQUIDS. APPLBCATION FILED MAY 20, 1918.

LQOQAWO Pat nted Jan. 3,1922,

' HEETS--SHEET I- Q v R fiverzkr -Z/Zvas kfaae v 26277722677 7? 2/;

H. J. ZIMMERIVIANN. ART OF EVAPORATING LIQUIDS.

APPLICATION FILED MRYZO, 1918.

1,402,467., Patented Jan. 3,1922

3 SHEETSSHEET H. J. ZJMMERMANN.

ART OF EVAPORATING LIQUIDS.

APPLICATION FILED MAY 20. 1918.

1,402,467,, Patented Jan. 3, 1922,,

3 SHEETSSHEET 3- 5. EMEFLERMANN, OF CHICAGO, ELZNOIS, ASSIGNOR, BY MESNE ASSIGNEENTE),

T9 R. srn'rmn COMPANY, A CORJPDRIATION GE ELINOIS'.

ear or nvaroaarnve riraurns.

Specification of Letters 'Patent.

Patented Jan. 3, 1922.,

Application filed may 20, 1918. serial No. 235,513.

one form of apparatus constructed in ac cordance with the invention; Fig. 2 is a similar view of a modified construction, and Fig. 3 is a similar view of a still further modification. I

Referring first to the construction illustrated in Fig. 1, the numeral 10 designates a vertical cylindrical evaporating chamber, having in the base thereof an upwardlydirected spray-nozzle 11, which sprays into an annular air-stream produced by a conical ring 12 secured to the side wall of the evapo rating chamber at the zone of the nozzle, and an inner cup 13 of substantial diameter and concentric with the nozzle. From the top of the evaporating chamber 10 a conduit 14 leads to a dust-collector 15, in which the gas or vapor-current is filtered through a screen 16 to separate the finely divided solids carried in suspension therein, these: solids being withdrawn from the base of the collector through the spout 17, into which they drop bygravity. From the base of the dustcollector chamber a conduit 18leads to a heat-exchanger 19, which is in the form of a casing having vertical heating tubes 20 for the passage of the gases or vapors delivered by the conduit 18. From the base of the heat-exchanger 19 a conduit 21 conducts the vapors or gases to the inlet side of a centrifugal blower 22,, the outlet side of which discharges into a cooler or condenser 23 comprising a casing similar to the heat-exchanger 19, but having its tubes 24: kept filled with a cooling agent, such as water, which flows through the tubes, as is indicated by the arrows. The gases or vapors delivered by the blower 22 pass around the tubes 24, and are next delivered to the heatplied, so as to effect complete evapo exchanger 19 in which they pass around the tubes 20. Beyond the heat-exchanger there is provided a heating chamber 25 filled with radiating coils 26, or otherwise heated.

The apparatus described in the foregoing is preferably operated in the following manner: The blower 22 is set in motion to cause a circulation of the air through the system in the direction indicated by the arrows. Cooling water is supplied to the tubes 24; or" the cooler and steam or other heating fillld to the radiating coils 26 of the heater. The liquid to be evaporated, for example milk, from which it is desired to recover the solid constituents in a dry form, is introduced under appropriate pressure through the i102 zle 11, by the agency of which it is subdi- J2 y vlded n the iorm ofa nne spray. This spray s sub ected at its outer portions. and

0 0 1 T y when 1t has had time to fully develop, to the actlonof the annular blast of heated air ascending in the space between the wall. of the cup 13 and the cone 12. in the example given, the rate of introduction or" the milk will be adiusted to the volume temp and degree of saturation of the of the liquid constituents of the mill: w the chamber 10. The current of air now containing a considerable percentage of water vapor, and carrying in suspension the finely divided solids of the milk, is conveyed by the conduit 14 through the dust-filler 15 in which the milk solids are for one most part precipitated, being withdrawn from time to time or continuously through the spout 1?. air current substantially freed of its suspended solid matter passes by the conduit 18 to the heat-exchanger 19 and through the vertical tubes 20 thereof, being substantially reduced in temperatur in its passage through these tubes, the lost heat being given up to the air passing horizontally through the heat-exchanger and around the tubes 20 thereof, as will later appear. riccording to the degree of cooling effected in the heat-exchanger tubes 20 and to the degree of saturation of the air current, there may be more or less condensation at this point. Any condensate thus obtained will drain to the base of the conduit 21, from which it may be withdrawn through the The moisture-laden and heated i trapped outlet 21. The partially cooled air current, after passing through the blower '22, is delivered to the cooler or condenser 23,

tively low temperature, a temperature somewhat above that of the'cooling Water 24, and will be saturated with water vapor at this temperature. This cooled and saturated air current now passes around the tubes of the heat-exchanger 19, in which its tem- .a condition of unsaturation. heating and drying effect obtained by the heat-exchanger 19 is supplemented by the perature is considerably elevated,being thereby proportionately dried, that is, brought to The initial radiating coils 26, by the aid of which circulating air current is further elevated in temperature, and thus rendered comparatively dry. In this heated and relatively dry condition the air current now re-enters the base of the evaporating chamber 10, thus beginning a new cycle.

It will be noted as characteristic of the method of operation described that there is continuously employed for the evaporation of the liquid the same body of drying medium (in the example given this medium being air). The drying medium circulates through a closed system of conduits, including the evaporating chamber, dust-collector, heat-exchanger, condenser, or cooler, through the other side of the heat-exchanger, through a heater and back to the evaporating chamber, the circulation being obtained by a blower included within the system. The

-evaporating medium is therefore succesin the heat-exchanger, further heated and dried in the heater, to be again cooled and rendered partially saturated by evapora tion of the spray Within the evaporating chamber.

Under uniform running conditions it-is. of course, self-evident that the amount of liquid condensate withdrawn from the traps .21 23 must equal the rate of evaporation from the spray nozzle 11, since the system is entirely closed, liquid only being admitted and liquid only withdrawn. By virtue of this condition the method of operation .described 1s particularly advantageous not only from the standpoint of economy in the use of heat, but likewise in the protection of the liquid to be evaporated and of the solids derived therefrom from the possibility of contamination, which inevitably would result from the employment of a system in which the evaporation was carried out by the continuous introduction of atmospheric air into the apparatus. Furthermore, the continued use of the same gaseous evaporating medium carries with it the possibility of employing a relatively expensive gas, such, for example, as carbon dioxide, nitrogen, or oxygen, where it is desired either to prevent oxidation or other chemical change in the product, or to effect a certain predetermined chemical change.

In Fig. 2 I have'illustrated a modification of the apparatus of Fig.1, this last construction being identical with that heretofore described, save for the fact that the system is an open one instead of a closed or circulating one. Thus, in Fig. 2 the air enters the blower 22 directly from the atmosphere, and this air being of itself relativelydry, therefore does not require the action of the cooler and condenser 23. In the construction shown in Fig.2 therefore, the outlet side of the blower is connected directly with the heat-exchanger 19, and the heated air passing through the tubes 20 of the heat-exchanger is itself discharged directly to the atmosphere. The advantage of economy of heat is attained in Fig. 2 as in Fig. 1.

In Fig. 3 I have illustrated a further modification of the apparatus of 1. The construction of Fig. 3 differs from that of. Fig. 1 only in that the heat-exchanger is omitted from the circulating system. Thus, in Fig. 3 the blower 22 has its inlet side connected directly with the conduit 18, which leads from the baseof the dust-collector 15. The outlet side of the blower 22 discharges directly into the cooler and condenser 23, the entire duty of lowering the temperature and condensing out the moisture from the circulating atmosphere being in" this construction assumed by the cooler and condenser. This construction retains the advantages of the construction of Fig. 1 in so far as the same are resultant upon the use of a continuously circulating evaporating medium.

While I have in the foregoing particu-.

larly described a preferred embodiment of my invention. together with some'variants thereof, it will be understood that this is illustrative only, and for the purpose of making the invention more clear, and that I do not regard the invention as limited to the construction or ,method of o eration specifically illustrated and describe except in so far as such limitations are included within the terms of the accompan ing claims, in which it is my intention to claim all novelty inherent in my invention as broadly as is permissible in view of the prior. art. 7

- What I claim is:- v

1'. The method of evaporating liquids, which consists in maintaining a circulation of a gaseous evaporating medium through a closed system 0 conduits, introducing e substance from which the liquid is to be evaporated, into the circulating medium, initially cooling the circulating medium beyond the point of liquid introduction by exchange of heat with the circulating medium entering the zone of evaporation, further cooling the circulating medium to condense therefrom the evaporated liquid, 'reheating the said cooled medium initially by exchange of ,heat as aforesaid, and

finally heating the circulating medium to restore. it to its, original condition before entering the zone of evaporation.

2. An evaporation apparatus comprising an evaporatlng chamber, means for introducing the liquid containing substance thereinto,-means for maintaining a closed circulation of a gaseous evaporating medium .7 having passed through said cooling means.

3. An evaporation apparatus comprising a closedsystem as follows: an evaporating chamber having means for introducing the liquid containing substance thereinto, a heat exchanger, means for conveying gaseous evaporating medium from the evaporating chamber to the warmer assages of the heat exchanger, a cooler and condenser, means for conveying gaseous evaporating medium from the heat exchanger to the cooler and condenser, a final heater, a connection from the cooler and condenser through the cooler passages of the heat exchanger'to the final heater and to the evaporating chamber and means for maintaining a circulation through the closed system.

HANS J. ZIMMERMANN. 

